/* An arena-like memory interface for the compiler.

 */

#ifndef Py_PYARENA_H

#define Py_PYARENA_H

#ifdef __cplusplus

extern "C" {

#endif

  typedef struct _arena PyArena;

  /* PyArena_New() and PyArena_Free() create a new arena and free it,

     respectively.  Once an arena has been created, it can be used

     to allocate memory via PyArena_Malloc().  Pointers to PyObject can

     also be registered with the arena via PyArena_AddPyObject(), and the

     arena will ensure that the PyObjects stay alive at least until

     PyArena_Free() is called.  When an arena is freed, all the memory it

     allocated is freed, the arena releases internal references to registered

     PyObject*, and none of its pointers are valid.

     XXX (tim) What does "none of its pointers are valid" mean?  Does it

     XXX mean that pointers previously obtained via PyArena_Malloc() are

     XXX no longer valid?  (That's clearly true, but not sure that's what

     XXX the text is trying to say.)

     PyArena_New() returns an arena pointer.  On error, it

     returns a negative number and sets an exception.

     XXX (tim):  Not true.  On error, PyArena_New() actually returns NULL,

     XXX and looks like it may or may not set an exception (e.g., if the

     XXX internal PyList_New(0) returns NULL, PyArena_New() passes that on

     XXX and an exception is set; OTOH, if the internal

     XXX block_new(DEFAULT_BLOCK_SIZE) returns NULL, that's passed on but

     XXX an exception is not set in that case).

  */

  PyAPI_FUNC(PyArena *) PyArena_New(void);

  PyAPI_FUNC(void) PyArena_Free(PyArena *);

  /* Mostly like malloc(), return the address of a block of memory spanning

   * `size` bytes, or return NULL (without setting an exception) if enough

   * new memory can't be obtained.  Unlike malloc(0), PyArena_Malloc() with

   * size=0 does not guarantee to return a unique pointer (the pointer

   * returned may equal one or more other pointers obtained from

   * PyArena_Malloc()).

   * Note that pointers obtained via PyArena_Malloc() must never be passed to

   * the system free() or realloc(), or to any of Python's similar memory-

   * management functions.  PyArena_Malloc()-obtained pointers remain valid

   * until PyArena_Free(ar) is called, at which point all pointers obtained

   * from the arena `ar` become invalid simultaneously.

   */

  PyAPI_FUNC(void *) PyArena_Malloc(PyArena *, size_t size);

  /* This routine isn't a proper arena allocation routine.  It takes

   * a PyObject* and records it so that it can be DECREFed when the

   * arena is freed.

   */

  PyAPI_FUNC(int) PyArena_AddPyObject(PyArena *, PyObject *);

#ifdef __cplusplus

}

#endif

#endif /* !Py_PYARENA_H */